PURPOSE: To easily perform gate treatment which becomes necessary after sealing a semiconductor device with a resin by using a film carrier.

CONSTITUTION: A runner 17 for pouring resin into the cavities 13 and 14 of a top and bottom forces 11 and 12 is installed to the bottom mold 12 only and, when a film carrier 1 is held between the forces 11 and 12, the surface Q of the carrier 1 composed only of a base film 2 is faced to the bottom force 12. The resin flowing through the runner 17 at the time of sealing adheres to the surface Q within the outer peripheral frame 2b of the film 2 as a remaining resin 22. Since the adhesiveness of the surface Q is lower than that of the lead forming surface P of the film 2, the remaining resin 22 can be easily removed from the section 2b.